#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <unordered_map>

using namespace std;

bool containsDuplicate(vector<int>& nums) {
    unordered_map<int, int> hash;

    for (auto e : nums)
    {
        hash[e]++;

        if (hash[e] == 2)
            return true;
    }

    return false;
}

int main()
{

	return 0;

}